A New Efficient Request-Based Comparable Encryption Scheme

Privacy-preserving comparisons over encrypted database is a hot topic in the current academic research. Recently, Furukawa [7] introduced a new primitive called request-based comparable encryption (comparable encryption for short) to achieve this target. Howver, one disadvantage of comparable encryption is that huge of the token and cipher text are required in the scheme and thus the computation and storage overload is heavy. In this paper, we propose an improved comparable encryption scheme by using the sliding window method, which is more efficient in the computation and storage workload than Furukawa´s scheme. Besides, the proposed scheme allows the users to obtain a variable trade-off between security and efficiency through adaptively setting the window size.